13 JavaScript one-liners that will make you look like an expert

1. Get a random Boolean value ( true / false )
2. Check if the provided date is a working day
3. Reverse a string
4. Check if the current tab is hidden
5. Check if a number is even or odd
6. Get the time from a date
7. Keep n decimal places
8. Check if an element is currently in focus
9. Check if the current browser supports touch events
10. Check if the current browser is on an Apple device
11. Scroll to the top of the page
12. Get the average value of the parameter
13. Fahrenheit/Celsius conversion

1. Get a random Boolean value ( true / false )

This function uses the Math.random() method and returns a boolean value ( true or alse ). Math.random creates a random number between 0 and 1, and we just check if it is above or below 0.5, which gives us a 50% chance of getting true or false.

const randomBoolean = () => Math.random() >= 0.5;
console.log(randomBoolean());

2. Check if the provided date is a working day

Using this method, we can check whether the date provided in the function is a weekday or a weekend day.

const isWeekday = (date) => date.getDay() % 6 !== 0;

console.log(isWeekday(new Date(2021, 7, 6)));
// true because it is Fridayconsole.log(isWeekday(new Date(2021, 7, 7)));
// false because it is Saturday

3. Reverse a string

There are several different ways to reverse a string. This is the simplest one, using the split(), reverse(), and join() methods.

const reverse = str => str.split('').reverse().join('');
reverse('hello world');     
// 'dlrow olleh'

4. Check if the current tab is hidden

Document.hidden (read-only property) returns a Boolean value indicating whether the page is hidden ( true ) or not ( false ).

const isBrowserTabInView = () => document.hidden;
isBrowserTabInView();

Off-site: I accidentally discovered that the iQiyi advertising playback time will only count down when the current tab is activated. When you leave the current tab, the countdown stops. I searched on Baidu and found this thing document.hidden .

document.hidden is a new API added to h5, which has compatibility issues when used.

var hidden
if (typeof document.hidden !== "undefined") {
    hidden = "hidden";
} else if (typeof document.mozHidden !== "undefined") {
    hidden = "mozHidden";
} else if (typeof document.msHidden !== "undefined") {
    hidden = "msHidden";
} else if (typeof document.webkitHidden !== "undefined") {
    hidden = "webkitHidden";
}
console.log("Is the current page hidden: " + document[hidden])

5. Check if a number is even or odd

const isEven = num => num % 2 === 0;
console.log(isEven(2));
// true
console.log(isEven(3));
// false

6. Get the time from a date

const timeFromDate = date => date.toTimeString().slice(0, 8);

console.log(timeFromDate(new Date(2021, 0, 10, 17, 30, 0))); 
// "17:30:00"

console.log(timeFromDate(new Date()));
// Print the current time

7. Keep n decimal places

const toFixed = (n, fixed) => ~~(Math.pow(10, fixed) * n) / Math.pow(10, fixed);
// Example toFixed(25.198726354, 1); // 25.1
toFixed(25.198726354, 2); // 25.19
toFixed(25.198726354, 3); // 25.198
toFixed(25.198726354, 4); // 25.1987
toFixed(25.198726354, 5); // 25.19872
toFixed(25.198726354, 6); // 25.198726

8. Check if an element is currently in focus

We can check whether an element is currently focused using the document.activeElement property.

const elementIsInFocus = (el) => (el === document.activeElement);
elementIsInFocus(anyElement)
// Returns true if in focus, false if not in focus

9. Check if the current browser supports touch events

const touchSupported = () => {
  ('ontouchstart' in window || window.DocumentTouch && document instanceof window.DocumentTouch);
}
console.log(touchSupported());
// If touch events are supported, true will be returned, otherwise false will be returned.

10. Check if the current browser is on an Apple device

const isAppleDevice = /Mac|iPod|iPhone|iPad/.test(navigator.platform);
console.log(isAppleDevice);

11. Scroll to the top of the page

const goToTop = () => window.scrollTo(0, 0);
goToTop();

12. Get the average value of the parameter

const average = (...args) => args.reduce((a, b) => a + b) / args.length;
average(1, 2, 3, 4);
// 2.5

13. Fahrenheit/Celsius conversion

const celsiusToFahrenheit = (celsius) => celsius * 9/5 + 32;
const fahrenheitToCelsius = (fahrenheit) => (fahrenheit - 32) * 5/9;
// Example celsiusToFahrenheit(15); // 59
celsiusToFahrenheit(0); // 32
celsiusToFahrenheit(-20); // -4
fahrenheitToCelsius(59); // 15
fahrenheitToCelsius(32); // 0

This concludes our article on 13 JavaScript one-line programs that will make you look like an expert. For more JavaScript content, please search 123WORDPRESS.COM’s previous articles or continue browsing the related articles below. I hope you will support 123WORDPRESS.COM in the future!

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